Color-screen for optical purposes.



G. RAMSTBIN-GSGHWIND. UOLOB SCREEN POE OPTICAL PURPOSES.

APPLIOATIOH nunnno. 12, 1906.

970,1 1 1 Patented Sept 13, 1910.

INVENTOR WITNESSES;

Mun-X,

. ATTORNEYS and a resident of Basel, Swit'zerl UNITED STATES PATENToamon.

cam. namsrnm-escnwmn, or BASEL, SWITZERLAND- COLOR-SCREEN FOB OPTICAIlPURPOSES.

Application filed December 12, 1906. Serial No. 7,461.

To'all'whom it may Concern -.Be it known that I, CARL. RAMSTEIN-Gscnwmu, a citizen of the Swiss Re ulilic, and: have invented certainnewand useful Improvements in Color-Screens for Optical Purposes, ofwhich the following is a specification.

My invention relatesto so-called color screens, also known as rayfilters or light filters, particularly such. as 'are 'used inphotography, generally in front of the camera lens, in orderto'obtainpictures in\ whichthe relative brightness of the colors to one anotherwill be reproduced with a satisfactory approximation to that found inthe original.

The object of my invention isto produce a color screen of the aboveindicated character which will be exceedingly simple, free fromdisturbing internal reflection and adapted to produce a uniformlyincreasing screening effect from one portion of the screento theopposite portion, so that a maximumspreenmg effect may be obtained forthe upperportion-of the picture (formed by the sky or snow-clad mountainsummits), with a gradually decreasing opacity to the I lower portion ofthe'picture, which generis'a perspective view of the mounted need not.so fiflrllite so as to form a single optical body,

f m ot er colors also.

is much darker all than the u er ortion.

' .fieference' is to be pp p had to the accompanying drawing in which Kigure 1 is a diagrammatic section illustrating the method of making my'new color screen; Fig. 2 is a cross section of the screen mounted in aholder so that me be readlly applied to a camera lens; Fig. 3 screen;andFig. 4 illustrates another form of my invention. v I

In ca 'out my invention,I'take a piece or plate A of colorless, orpractical] colorlessaglasaand another piece or late .of color glass,generally ellow, a though inventionis a plicab e to screens of" es'e twopieces of colorless and colored lass, the surfaces of whichbe pe ectlyplane or poli'shedgI y sing them together superficially after bringingthem into contact with eac other asiindicated'in Fi 1. The division lineor separating line w ich is shown in Figs. .1 :and 2, for the, sake'fofclearness, is not ob-v servableinpra'ctice, as the screen actuall formsasingle body of glass, although t colorless and colored glass be used andheated speciflcation'ot Letters Patent. Patented Sept. 13, 1910.

is made from. two pieces. These be fused together in the-manner describeeither while they are still'hot and soft from the manufacturing process,or any suitable plates, obtainable in the market, In? 0 until they areready r connection by superficial fusion as described; This first step,

and the comaving been accomplished heen allowed to posite glass bodyhaving cool, such body is ground both sides, as indicated by'the parallelines C, C in Fig. 1. That is, the portions a, b outside the lines C, Care removed, so that the completed article contains only materialbetween the lines C, C, .or rather, the parallel planes indicatedthereby. The new plate thus produced is cut into disks in the usualmanner, Figs. 2 and 3 showing such a disk D mounted in. a-holder Ehaving spring fingers E for adapting it: on a camera lensof ordinaconstruction. It will be seen that t e color screen produced in themanner above set forth consists pieces may at an an lo 011.

of colored glass in its entire thicknessat one end (the upper end) andofcolorless glass in its entire thickness at the other end (the lowerend), there being a gradual'transition in the proportions of coloredlass and colorless glass'from oneend to t e other. 7 The aplpearance ofthe screen therefore is strongly 7 ye ow (or otherwise colored) 'at oneend V the tint growing adually llghter toward the other end 'unt' itsentire deep earance. Thelowen portion of the screen is a solutelycolorless in its entire thickness for a material distance, viz, from thepoint 0 to' the point "d, the colored portion of the screen terminatingat Said point d which isata distance from the lower edge'c. Such a colorscreen when used in connection with a camera lens,

will give, the proper relative values" to the colors.'of' the sky,clouds, mountains etc,, and the lower parts of the picture. The effeetwill be amuch closer renditioh of the color relationsof theoriginalscenery or ohje'ct than when ordinary color sc e n are employed.The fact that there are no interior meetingsurfaces, "does away withthepossibility, of disturbingfinternal' reflections.

'urthermorp, by fusing the adjacent glass surfaces together, I make themfit each other ute accuracy (that is, without withabso .leaving anyspaces between them) and avoid any for carefully surfaces.

e only surfaces -w are grm din such hid in Fig. A. ln-any event,

term: color be glven ,a relative meaning. o

---1; A color screen for'optical purposes,

gen 11d are those designated by thelines C,

that is, the exposed; surfaces oi the finished 'color"screen.n Inpractice it will be as little ness.

If desired, I could'cut away the upper portion of the screen where itiscolored in' its entire thickness, above the) line H, thus producing ascreen of the character shown of-the screen (below the line f--. ,-F1gs.1, 2 and 4:) is colorless in its entire t ickness, "so

theta material portion of the-screenwill be of uniformtransparencyallowing. a maximum of li ht to pass therethrongh; The.

%ess as used in'the clenn's'is to Ielaim as my invention:

I consisting of an, integral body of glass, com

the colored partvdecreasing in'thickn the same thickone edge portionward one edge of the screen and terminating at :1, distance from saidedge, so that .a material portion of said screen, adj

edge, will be colorless in its entire thickness. 2, A. color screen foroptial purposes composed of a colorless part and a colore part, thecolored art decreasing in minating at a distance from said edge, so

that -a-material portion of said screen, adjacent'to such edge,-

will be colorless in its entire thickness;

thick n'ess toward one e ge of the screen and terposed-of a colorlesspart and a colored part,

ess to-' I acent to sick In testimony whereof, I have hereunto gsignedmy name in the presence of two subscribing witnesses. I

CARL RAMsrEm-Gsom. Witnesses: I l l (Jameson,

